Who's affected and why?

Charles Bonnet syndrome affects people who've lost most or all of their eyesight. It's more likely to occur if vision loss affects both eyes.

According to the Macular Society, up to half of all people with macular degeneration a gradual loss of central visionmay experience Charles Bonnet hallucinations at some time. It's thought there are more than 100,000 cases in the UK.

People of any age can be affected by Charles Bonnet hallucinations, but they tend to occur later in life after a person starts to lose their sight. The hallucinations often begin when a person's sight suddenly deteriorates.

The main cause of Charles Bonnet syndrome is thought to be vision loss and how the brain reacts to it. It's not clear how loss of vision leads to hallucinations, but research is beginning to help us better understand the relationship between the eyes and the brain.

When a person starts to lose their sight, their brain doesn't receive as much information as it used to. It's thought the brain sometimes responds by filling in the gaps with fantasy patterns or images that it's stored. These stored images are experienced as hallucinations.